1. Field of the Invention
This invention relates to liquid, solvent-free aqueous preparations for removing film-forming polymeric protective coatings, containing a combination of alkanolamines and hydrotropic substances acting as solution promoters, optionally together with pH-regulators, thickeners, surfactants, corrosion inhibitors, biocides and/or dyes.
2. Description of the Prior Art
Consumer goods surface-treated with lacquers or paints of various origin, for example automobile bodies, window frames of metal or the like, may be provided with film-forming polymeric protective coatings for protection against mechanical damage and the effects of weather during transport and/or storage. These protective coatings may cover any materials which are used, for example, on the exterior of an automobile body, such as lacquered and metallic surfaces, plastics, rubber and glass.
The materials used for protective coatings such as these, particlarly for automobile bodies, are generally waxes which are applied with organic solvents, preferably hydrocarbons or lower monohydric alcohols. More recently, solvent-containing and aqueous polymer dispersions have also been available on the market for coating automobile bodies.
When the articles coated with the polymeric protective film are prepared for use, the polymer film is removed. In many cases, this is done using the same organic solvents that were used in the application of the protective layers, i.e. preferably organic solvents, such as hydrocarbons or lower monohydric alcohols. The use of alkaline inorganic products in cleaning solutions for removing polymeric protective coatings is known from Japanese Pat. No. 75 67 845. Disadvantages of the above-mentioned cleaning processes include pollution of the waste water by organic solvents and/or the inorganic salts, which is made even more serious by the fact that the waste water accumulating has to be neutralized. In addition, the alkaline products endanger the coated materials used, particularly lacquered surfaces. Discoloration of the metals used, staining or oxidation, and embrittlement or swelling of plastics and rubber can all be expected to occur.
The removal of a wax-based preserving and protective coating with a mixture of water and steam at a temperature of from 90.degree. to 95.degree. C. is mentioned in German Application No. 29 26 197. The removal of the protective film in this way is not only very energy-intensive, it is also hazardous because of the risk of scalding with hot water or steam.
Coatings which cannot be removed with cleaner solutions, but instead have to be peeled off the articles coated therewith are described in German Application No. 22 63 311, in French Pat. No. 2,295,100 and in Japanese Application No. 79 07 303. The disadvantage of this process lies in the considerable time required for completely peeling off the protective material from the surface coated therewith, which must be regarded as impracticable. In addition, where this process is applied, residues of the coating materials generally remain behind in difficult to reach places in automobile bodies, for example.